The so-called ‘ozone hole’ has been reduced this year to 23.2 million square kilometers – the Iberian Peninsula has an area of 583,000 square kilometers – between September 7 and October 13, NASA and the United States Oceanic and Atmospheric Administration (NOAA). The South Pole region with low ozone concentration was slightly smaller last southern spring, when the ‘hole’ recorded its annual maximums than in 2021 – when it reached 23.3 million square kilometers – and was “well above below the average observed in 2006, when the size of the ‘hole’ reached its maximum.
Ozone (O3) is a gas found mainly (90%) in the stratosphere, between 10 and 50 kilometers high. It acts as a natural shield against harmful ultraviolet radiation, which causes skin cancer and cataracts. In the mid-1970s, scientists discovered a worrying reduction in the ozone layer over Antarctica due to the destruction of this gas by chlorofluorocarbon compounds (CFCs) used in refrigerators and air conditioning systems. In 1987, 197 countries signed the so-called Montreal Protocol for the elimination of chlorofluorocarbons, which has since translated into the progressive recovery of Antarctic ozone. According to scientists’ forecasts, the layer of this gas over the South Pole could fully recover by 2050.
“As time goes by, steady progress is being made and the hole is shrinking,” Paul Newman, chief scientist for Earth sciences at NASA’s Goddard Space Flight Center, said of the latest data. “We are seeing some fluctuations, as weather and other factors cause the numbers to vary slightly from day to day and week to week. But, in general, (the ‘ozone hole’) has decreased in the last two decades,” says this expert.
NASA and NOAA scientists monitor the ‘ozone hole’ with instruments aboard the Aura, Suomi NPP and NOAA-20 satellites. On October 5, these satellites observed a single-day maximum ‘ozone hole’ of 26.4 million square kilometers, slightly larger than last year.
Additionally, NOAA scientists working at the Amundsen-Scott South Pole Station, located at the geographic south pole, also record the thickness of the ozone layer by releasing balloons carrying instruments that measure the total amount of ozone between the surface terrestrial and the edge of space as they ascend. The global average ozone column is about 300 Dobson units. On October 3, NOAA scientists recorded a minimum ozone value over the South Pole of 101 Dobson units. At that time, NASA explains, ozone was almost completely absent at altitudes between 14 and 21 kilometers, a pattern very similar to last year.
Some scientists were concerned about the possible impact of the eruption of the underwater volcano Hunga Tonga-Hunga Ha’apai (Tonga), which produced a tsunami in January that hit the islands of Tonga and a tidal wave in Fiji. They feared that something similar to 1991 would happen, when the Pinatubo eruption (Philippines) released enormous amounts of sulfur dioxide that affected the ozone layer. This year, however, no direct impacts of the Tonga volcano eruption on Antarctica have been detected.